Organic electroluminescent display having light scattering film

ABSTRACT

An organic electroluminescent display includes a pair of substrates; an organic electroluminescent device between the pair of substrates, including: a pair of electrodes of an anode and a cathode, and a light-emitting layer between the pair of electrodes; and a light scattering film on a substrate on the viewing side of the pair of substrates, including: a transparent substrate film, and a light scattering layer which contains a light transmitting resin and a light scattering particle having a particle size of from 0.3 μm to 1.2 μm, wherein a ratio of (np/nb) is from 0.80 to 0.95 or from 1.05 to 1.35, taking a refractive index of the light scattering particle and the light transmitting resin as np and nb, respectively.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic electroluminescent display.

2. Description of the Related Art

Organic electroluminescent (organic EL) displays are self-emitting typethin displays, and have advantages of display performance such that highin visibility, and small in viewing angle dependency, as compared withliquid crystal displays. Further, in addition to the advantages ofcapable of making weight light and thinning, they have the possibilityof realizing new shapes of displays that have been unrealized hithertoby using flexible substrates.

Organic EL displays have excellent characteristics as described above.However, although organic EL displays are excellent in viewing angledependency as compared with liquid crystal displays, the refractiveindex of each layer including a light-emitting layer constituting thedisplays is generally higher than the refractive index of air, and sincethe refractive indexes are different, emission spectrums are differentdue to the angles to the displays by a light interference effect. Thiscauses a tin variation depending on the viewing angle of the viewer, andmay influence viewing angle characteristics.

Further, for the purpose of the improvement of frontal luminance, theuse of a photo-resonance effect by the reflection on the surface betweenthe electrodes positioned on both sides of the light-emitting layer, orthe use of a prism sheet or the like is exemplified. In that case, theinfluence of viewing angle dependency is conspicuous.

As a means for improving viewing angle dependency, a method of usinglight scattering means is disclosed. For examples an organic EL displaywhose viewing angle characteristic is improved by providing a colorfilter and a light scattering means on the side for collecting light ofthe organic EL device is disclosed (e.g., refer to JP-A-11-329742 (Theterm “JP-A” as used herein refers to an “unexamined published Japanesepatent application”.)). Specifically, as the scattering means,dispersing inorganic fine particles in the color filter, or providing alight scattering layer wherein inorganic fine particles are dispersed incontiguous to the color filter is disclosed.

Further, an organic EL display provided with a light scattering layercontaining light scattering particles on the side to collect lights fromthe light-emitting layer to improve a viewing angle dependency isdisclosed (e.g., refer to JP-A-2002-270365).

Further, for the improvement of viewing angle characteristics, it isproposed to provide a diffusing layer having haze of 80% or more (e.g.,refer to JP-A-2003-173877). Specifically, a method of forming ascattering layer on a fluorescent layer by spin coating is shown.However, a light scattering property of the light scattering layer thatis preferred for the improvement of viewing angle characteristics is notalways sufficient by merely controlling haze.

SUMMARY OF THE INVENTION

In JP-A-11-329742, JP-A-2002-27036S, and JP-A-2003-173877, the lightscattering layer is formed directly on the color filter, the fluorescentlayer and the like. This is certainly preferred in the viewpoint of theimprovement of a blur of letters, but not preferred in the points ofmanufacturing costs, the thickness of the light scattering layer, andselectivity of the particle size of light scattering particles, and alsoin the organic electroluminescent device liable to be deteriorated bythe influences of moisture content, organic solvents and ultravioletrays, it is not preferred in the points of manufacturing suitability,durability, selectivity of the kind of light transmitting resin of thefight scattering layer. It is rather preferred to use a light scatteringfilm having provided on a transparent support a light scattering layerhaving desired light scattering characteristics on the surface of adisplay.

The representative construction of an organic EL device is shown inFIG. 1. As shown in FIG. 1, an organic EL display fundamentally has theconstruction comprising lamination of TFT substrate 1, rear electrode 2,organic layer 3 consisting of two or three layers including alight-emitting layer, transparent or translucent electrode 4, andtransparent substrate 5. Positive holes injected from rear electrode 2and electrons injected from translucent electrode 4 are recombined inorganic layer 3 to excite a fluorescent substance and emit lights Thelight emitted from organic layer 3 outgoes from transparent substrate 5directly or by reflection on rear electrode 2 formed of aluminum or thelike. In the construction, the lights reflected on the surface on theside of each light-emitting layer of rear electrode 2 and transparent ortranslucent electrode 4 are optically resonated, by which the couplingout efficiency of lights is bettered and surface luminance can beimproved. However, there arises a problem that the directivity of lightbecomes stronger and viewing angle dependency of tint becomesconspicuous, so that the improvement is desired.

An aspect of the invention is to provide an organic EL display improvedin viewing angle dependency. Another aspect is to provide an organic ELdisplay restrained in a blur of letters, that can be easilymanufactured, and having high productivity and high durability. Theseaspects of the invention can be achieved by the following organicelectroluminescent display.

-   (1) An organic electroluminescent display comprising:

a pair of substrates;

an organic electroluminescent device between the pair of substrates,comprising:

-   -   a pair of electrodes of an anode and a cathode, and    -   a light-emitting layer between the pair of electrodes; and

a light scattering film on a substrate on the viewing side of the pairof substrates, comprising:

-   -   a transparent substrate film, and    -   a light scattering layer which contains a light transmitting        resin and a light scattering particle having a particle size of        from 0.3 μm to 1.2 μm,

wherein

a ratio of (np/nb) is from 0.80 to 0.95 or from 1.05 to 1.35, taking arefractive index of the light scattering particle and the lighttransmitting resin as np and nb, respectively.

-   (2) The organic electroluminescent display of (1), wherein

the particle size of the light scattering particles is from 0.4 μm to1.0 μm.

-   (3) The organic electroluminescent display of (1), wherein

the light scattering film has asymmetry (g) of from 0.70 to 0.98.

-   (4) The organic electroluminescent display of (1), wherein

the light scattering film has a scattering efficiency (e) of from 0.05to 12.0.

-   (5) The organic electroluminescent display of (1), wherein

a ratio of (I₃₀/I₀) is from 0.08 to 0.99, taking a scattered lightintensity of a scattered light profile by a gonio-photometer at outputangle 0° and 30° as I₀ and I₃₀, respectively.

-   (6) The organic electroluminescent display of (1), wherein

the light scattering film is an antireflection film comprising a lowrefractive index layer, directly or via any other layer, on a surface ofthe light scattering layer, and

an average value of mirror reflectivity at 5° incidence of theantireflection film in a wavelength region of from 450 to 650 nm is from0.1% to 2.0%

-   (7) The organic electroluminescent display of (6), wherein

the tints of regularly reflected light of the antireflection film to 5°incident light of CIE standard light source D65 in a wavelength regionof from 380 nm to 780 nm as a* and b* values of CIE1976L*a*b* colorspace are respectively in a range of −8≦a*≦8 and −10≦b*<10.

-   (8) The organic electroluminescent display of (1), wherein

a center line average roughness (Ra) on a surface of the lightscattering film is from 0.003 μm to 0.20 μm.

-   (9) The organic electroluminescent display of (1), wherein

the transparent substrate film has a thickness of from 10 μm to 80 μm.

-   (10) The organic electroluminescent display of (1) wherein

the transparent substrate film has a water vapor permeability of 0.01g/m²·day or less at 40° C. 90% RH.

-   (11) The organic electroluminescent display of (1), wherein

a maximum value of emission wavelength is from 350 nm to 700 nm, and

[(x₆₀-x₀)²+(y₆₀-y₀)²]^(1/2) is from 0.05 to 0.3, taking a colorcoordinate of emission spectrum in a direction of output angle of 0° and60° on xy chromaticity diagram as (x₀, y₀) and (x₆₀, y₆₀), respectively.

-   (12) The organic electroluminescent display of (1), wherein

a light reflected between the surfaces of both electrodes is opticallyresonated.

-   (13) The organic electroluminescent display of (1), wherein

the substrate on the viewing side has a thickness of from 0.01 mm to0.70 mm.

-   (14) The organic electroluminescent display of (1), wherein

the substrate on the viewing side has a thickness of from 0.03 mm to0.30 mm.

-   (15) The organic electroluminescent display of (1) wherein

at least one of the surface and the edge of the substrate on the viewingside is coated with a polymer.

-   (16) The organic electroluminescent display of (1), wherein

the substrate on the viewing side is a gas barrier film,

-   (17) An organic electroluminescent display comprising:

a pair of substrates; and

an organic electroluminescent device between the pair of substrates,comprising:

-   -   a pair of electrodes of an anode and a cathode, and    -   a light-emitting layer between the pair of electrodes

wherein

at least a substrate on the viewing side of the pair of substrates is alight scattering film comprising.

-   -   a gas barrier film having a water vapor permeability of 0.01        g/m²·day or less at 40° C. 90% RH, and    -   a light scattering layer which contains a light transmitting        resin and a light scattering particle having a particle size of        from 0.3 μm to 1.2 μm; and

a ratio of (np/nb) is from 0.80 to 0.95 or from 1.05 to 1.35, taking arefractive index of the light scattering particle and the lighttransmitting resin as np and nb, respectively.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a typical view showing an organic EL display using aphoto-resonance effect;

FIG. 2 is a typical view showing an example of a light scattering filmcontaining a transparent substrate film and a light diffusing layer foruse in the invention;

FIG. 3 is a typical view showing an example of an antireflection filmcontaining a transparent substrate film, a light scattering layer and alow refractive index layer for use in the invention;

FIG. 4 is a schematic diagram showing a fundamental constitution of anorganic EL display;

FIG. 5 is a typical view showing the constitution of one embodiment ofthe invention; and

FIG. 6 is a typical view showing the constitution of one embodiment ofthe invention,

wherein

-   -   1 denotes TFT substrate    -   2 denotes Back electrode    -   3 denotes Organic layer including light-emitting layer    -   4 denotes Transparent or translucent electrode    -   5 denotes Transparent substrate    -   10 denotes Light scattering film 1    -   11 denotes Light scattering film 2    -   20 denotes Transparent substrate film    -   30 denotes Light scattering layer    -   31 denotes Light transmitting resin    -   41 denotes Light scattering particle    -   50 denotes Low refractive index layer    -   100 denotes Organic EL display    -   110 denotes TFT substrate    -   120 denotes Lower electrode    -   130 denotes Organic EL layer    -   140 denotes Upper electrode    -   150 denotes Gas barrier layer    -   160 denotes Transparent substrate    -   170 denotes Adhesive layer.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in detail below. The descriptionof “A to B” in the specification of the invention means “A or more and Bor less”. Further, “organic EL” means “organic electroluminescence”.

One embodiment of the organic electroluminescent display in theinvention is an organic electroluminescent display having, between apair of substrates, an organic electroluminescent device of a structurehaving a pair of electrodes of the anode and the cathode and alight-emitting layer between the pair of electrodes, wherein a substrateon the viewing side of the pair of substrates is a light scattering filmhaving a transparent substrate film and a light scattering layer, thelight scattering layer contains a light transmitting resin and lightscattering particles, the particle size of the light scatteringparticles is in the range of 0.3 μm or more and 1.2 μm or less, and theratio of the refractive index of the list scattering particles (np) tothe refractive index of the light transmitting resin (nb) (np/nb) is0.80 or more and 0.95 or less, or 1.05 or more and 1.35 or less.

Another embodiment of the organic electroluminescent display in theinvention is an organic electroluminescent display having, between apair of substrates, an organic electroluminescent device of a structurehaving a pair of electrodes of the anode and the cathode and alight-emitting layer between the pair of electrodes, wherein at least asubstrate on the viewing side of the substrates is a light scatteringfilm having a gas barrier film and a light scattering layer, the lightscattering layer contains a light transmitting resin and lightscattering particles, the particle size of the light scatteringparticles is in the range of 0.3 μm or more and 1.2 μm or less, and theratio of the refractive index of the light scattering particles (np) tothe refractive index of the light transmitting resin (nb) (np/nb) is0.80 or more and 0.95 or less, or 1.05 or more and 1.35 or less.

The construction of the organic electroluminescent display (organic ELdisplay) in the invention will be described below.

A Light Scattering Film:

A light scattering film comprising a transparent substrate film havingformed thereon light scattering layer is used in the invention. The useof the light scattering film is advantageous in that the productivity ishigh as compared with the case where a light scattering layer isdirectly provided on a color filter and an EL device, manufacturingcosts can be reduced, durability can be heightened, and selectivity ofmanufacturing process and selectivity of material and film thickness arehigh. Further, the light scattering layer also has the function of ahard coat layer of the surface at the same time, so that a hard coatlayer does not have to be provided separately, and this is an excellentadvantage of the invention.

FIG. 2 is a typical cross-sectional view showing a fundamental structureof a light scattering film. Light scattering film 10 shown in FIG. 2comprises transparent substrate film 20 and light scattering layer 30.Light scattering layer 30 contains light scattering particles 41 inlight transmitting resin 31. Light scattering layer 30 may comprise aplurality of layers. Two or more kinds of light scattering particles maybe used. As shown in FIG. 3, antireflection film 11 having theconstruction of lamination of low refractive index layer 50 on theopposite side of transparent substrate film 20 of light scattering layer30 is more preferred in the points of not only improvement of viewingangle characteristics but also bright room contrast and prevention ofmirroring in the surface of a display.

A Light Scattering Layer:

Light scattering layer 30 contains light scattering particles 41 andlight transmitting resin 31. For the purpose of improving viewing anglecharacteristics of an organic EL display, it is important to optimizescattered light profile (the angle dependency of scattered light).Although a haze value is sometimes used as a simple index of scattering,angle dependency is not revealed, so that it is difficult to defineoptimal scattering by a haze value alone. Scattered light profile can beadjusted by the refractive index and the particle size of each of lightscattering particles 41 and light transmitting resin 31. In general,when particles having different refractive index from that of a lighttransmitting resin are present in the light transmitting resin, thelight incident upon the particles are scattered by the particles. Thelight scattered and returned to the incident side is called a backwardscattering factor and the light scattered forward is called a forwardscattering factor hereafter. As a result of examination of scatteredlight profile suitable for the improvement of viewing angle dependencyof the organic EL display, it has been found that, when a backwardscattering factor is small (a forward scattering factor is large), ascattering efficiency of forward scattering is high (a direct advancefactor is small) and scattering of 30° factor in the forward scatteringfactor satisfies necessary amount, a preferred improving effect ofviewing angle characteristics can be obtained and original design ofscattering is necessary.

Scattered light profile of a light scattering layer is described indetail below. A forward scattering factor can be defined by asymmetryparameter g (the value of the coefficient of scattering anisotropy; thecalculated value described in Bohren-Huffman, Absorption and Scatteringof Light by Small Particles, 3.4). The asymmetry parameter g ispreferably from 0.70 to 0.98, and more preferably from 0.80 to 0.95.When the parameter is less than 0.70, backward scattering is great andthereby luminance tends to lower, while when the parameter is greaterthan 0.98, scattering efficiency is worse and thereby an improvingeffect of viewing angle dependency tends to be little.

Scattering efficiency e can be computed as e=n×C from scattering crosssection C and number of particles n based on Mie scattering theory.Scattering efficiency e is preferably from 0.05 to 12.0, more preferablyfrom 0.05 to 3.0, still more preferably from 0.5 to 2.5, and especiallypreferably from 1.0 to 2.5. When scattering efficiency e is less than0.05, the amount of scattering is insufficient and the improving effectof the characteristics of viewing angle of tint tends to be little,while when it is greater than 12.0, the amount of scattering is too big,and thereby frontal luminance and feeling of discoloration tend toworsen.

In connection with a 30° factor in the forward scattering factor, ascattering profile can be measured with a gonio-photometer. For example,a light scattering film is arranged vertically to incident light with anautomatic varied angle photometer Model GP-5 (manufactured by MurakamiColor Research Laboratory) and the scattered light profile is measured.With the value in the direction of 0° (direct advance direction) of theforward scattering factor being I₀, and the value in the direction of30° (the direction inclined by 30° from the direct advance direction) ofthe forward scattering factor being I₃₀, I₃₀/I₀ is preferably from 0.08to 0.99, more preferably from 0.08 to 0.80, and especially preferablyfrom 0.5 to 0.8. When I₃₀/I₀ is less than 0.08, the effect of angledependency improvement tends to be little, while when it is greater than0.99, frontal luminance tends to lower.

When three parameters of asymmetry parameter g, scattering efficiency e,and I₃₀/I₀ are satisfied at the same time, especially preferredperformances can be revealed.

For achieving the scattering profile as described above, it is necessarythat the ratio of the refractive index of light scattering particles(np) to the refractive index of a light transmitting resin (nb) (np/nb)and the particle size of light scattering particles be selected intopreferred ranges.

Light Scattering Particles:

It is necessary for the refractive index of light scattering particles(np) to make the ratio to the refractive index of a light transmittingresin (nb) (np/nb) to a specific range. The ratio of the refractiveindex of light scattering particles (np) to the refractive index of alight transmitting resin (nb) (np/nb) is necessarily 0.80 or more and0.95 or less, or 1.05 or more and 1.35 or less, and preferably 0.80 ormore and 0.92 or less, or 1.08 or more and 1.20 or less. When (np/nb) issmaller than 0.80 or larger than 1.35, backward scattering is great andfrontal luminance tends to lower, while when it is larger than 0.95 andsmaller than 1.05, a sufficient scattering effect cannot be obtained andthe effect of viewing angle dependency improvement is not sufficient.The particle size of light scattering particles is important as well asthe difference in refractive index. The particle size of lightscattering particles is from 0.3 μm to 1.2 μm, preferably from 0.4 μm to1.0 μm, and more preferably from 0.5 μm to 1.0 μm. When the particlesize is less than 0.3 μm, backward scattering is great and thereby thereis a problem that luminance lowers, while when the particle size is morethan 1.2 μm, preferred scattered angle distribution cannot be obtainedand the effect of angle dependency improvement is not sufficient. It isnecessary to use light scattering particles having these refractiveindex and particle size as described above at the same time to obtainthe advantage of the invention.

Light scattering particles may be used by one kind alone, or a pluralityof kinds may be used in combination. Two or more kinds of particleshaving the above scattered light profile may be used in combination, orit is also preferred to use one kind of particles having the abovescattered light profile and form surface unevenness with other greaterparticles.

Light scattering particles may be organic fine particles or inorganicfine particles. As light scattering particles, particles having hightransparency and the value of refractive index difference between thatof light transmitting resin as described above are especially preferred.As organic fine particles, polymethyl methacrylate beads (refractiveindex: 1.49), acryl beads (refractive index: 1.50), acryl-styrenecopolymer beads (refractive index: 1.54), melamine beads (refractiveindex: 1.57), high refractive index melamine beads (refractive index:1.65), polycarbonate beads (refractive index: 1.57), styrene beads(refractive index: 1.60), crosslinked polystyrene beads (refractiveindex: 1.61), polyvinyl chloride beads (refractive index: 1.60),benzoguanamine-melamine-formaldehyde beads (refractive index: 1.68), andsilicone beads (refractive index: 1.50) are used. As inorganic fineparticles, silica beads (refractive index: 1.44), alumina beads(refractive index: 1.63), titanium oxide beads (refractive index ofanatase type: 2.50, rutile type: 2.70), zirconia oxide beads (refractiveindex: 2.05), and zinc oxide beads (refractive index. 2.00) are used. Byusing light transmitting resin 31 having refractive indexes suitable forrespective particles, it is possible to make difference in refractiveindex between light transmitting resin and light scattering particles inthe above-mentioned specific range. As preferred organic fine particles,polymethyl methacrylate beads (refractive index: 1.49), acryl beads(refractive index: 1.50), acryl-styrene copolymer beads (refractiveindex: 1.54), melamine beads (refractive index: 1.57), high refractiveindex melamine beads (refractive index: 1.65), polycarbonate beads(refractive index: 1.57), styrene beads (refractive index: 1.60),crosslinked polystyrene beads (refractive index: 1.61), polyvinylchloride beads (refractive index: 1.60),benzoguanamine-melamine-formaldehyde beads (refractive index: 1.68), andsilicone beads (refractive index: 1.50) are used. As preferred inorganicfine particles, silica beads (refractive index: 1.44) and alumina beads(refractive index: 1.63) are used. As a light transmitting resin used inthe light scattering layer, from the points of selectivity of materials,interference unevenness, surface condition, costs, etc., materialshaving a refractive index of 1.50 to 1.54 obtainable by curing ordinarypolyfunctional polymers are preferably used. In that case, as a resinparticle which obtains a refractive index difference necessary forrevealing a scattering property preferable in the invention and whichhas advantage in productivity such as a sedimentation property, highrefractive index melamine beads (refractive index: 1.65) andbenzoguanamine-melamine-formaldehyde beads (refractive index: 1.68) areespecially preferred. As a high refractive index melamine bead, amelamine-silica crosslinked particle (OPTOBEADS, manufactured by NissanChemical Industries, Ltd.) can be also used.

The light scattering particles are preferably contained in an amount offrom 5 to 50 mass parts per 100 mass parts of the light transmittingresin, more preferably from 10 to 45 mass parts, and especiallypreferably from 20 to 40 mass parts. When the content of the lightscattering particles is less than 5 mass parts per 100 mass parts of thelight transmitting resin, light scattering tends to be insufficient, andwhen the amount is more than 50 mass parts back scattering tends tobecome large and film strength tends to be weakened.

In the case of the above light scattering particles, the lightscattering particles are liable to precipitate in the light transmittingresin, so that inorganic fillers such as silica and the like may beadded for the purpose of precipitation prevention. Incidentally, themore the addition amount of inorganic fillers, the more effective is theprecipitation prevention of the light scattering particles, but thetransparency of the film is mal-affected or the scattering property isinfluenced. Accordingly, it is preferred to add inorganic fillers havinga particle size of 0.1 μm or less difficult to affect the scatteringproperty to a Light transmitting resin in an amount of less than 1 mass% so as not to impair transparency of a coated film.

A Light Transmitting Resin:

As light transmitting resin 31, resins curable with ultraviolet,electron beams or heat, i.e., three kinds of ionizing radiation-curableresins, ionizing radiation-curable resins mixed with a thermoplasticresin and a solvent, and thermosetting resins are used. The thickness ofa light scattering layer is generally from 0.5 to 50 μm or so,preferably from 1 to 20 μm, more preferably from 2 to 10 μm, and mostpreferably from 3 to 7 μm. The refractive index of a light transmittingresin is preferably from 1.48 to 2.00, more preferably from 1.50 to1.90, still more preferably from 1.50 to 1.85, and especially preferablyfrom 1.50 to 1.80. When the refractive index is lower than 1.48, thestrength tends to lower, and when it is higher than 2.00, the strengthtends to lower and interference unevenness tends to occur easily.

Binders for use in light transmitting resins are preferably polymershaving saturated hydrocarbon or polyether as the main chain, and morepreferably polymers having saturated hydrocarbon as the main chain.Binders are preferably crosslinked. It is preferred to obtain thepolymers having saturated hydrocarbon as the main chain bypolymerization reaction of ethylenic unsaturated monomers. To obtaincrosslinked binders, it is preferred to use monomers having two or moreethylenic unsaturated groups.

The examples of the monomers having two or more ethylenic unsaturatedgroups include esters of polyhydric alcohol and (meth)acrylic acid(e.g., ethylene glycol di(meth)acrylate, 1,4-dicyclohexane diacrylate,pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate,trimethylolpropane tri(meth)acrylate, trimethylolethanetri(meth)acrylate, dipentaerythritol tetra(meth)acrylate,dipentaerythritol penta(meth)acrylate, dipentaerythritolhexa(meth)acrylate, 1,3,5-cyclohexanetriol trimethacrylate, polyurethanepolyacrylate, and polyester polyacrylate), vinylbenzene derivatives(e.g., 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloyl ethyl ester,1,4-divinylcyclohexanone), vinylsulfone (e.g., divinylsulfone),acrylamide (e.g., methylenebisacrylamide), and methacrylamide. Of thesemonomers, acrylate and methacrylate monomers having at least threefunctional groups, and acrylate monomers having at least five functionalgroups are preferred in the point of film hardness, that is, scratchresistance. Mixtures of dipentaerythritol pentaacrylate anddipentaerythritol hexaacrylate are commercially available and especiallypreferably used. These monomers may be used by one kind alone, or may beused as mixtures of two or more kinds.

These monomers having ethylenic unsaturated groups can be hardened bydissolving in a solvent together with various kinds of polymerizationinitiators and other additives, coating and drying, and thenpolymerization reaction with ionizing radiation or heating.

In place of or in addition to the monomers having two or more ethylenicunsaturated groups, a crosslinking structure may be introduced intobinders by the reaction of crosslinkable groups. The examples ofcrosslinkable functional groups include an isocyanate group, an epoxygroup, an aziridine group, an oxazoline group, an aldehyde group, acarbonyl group, a hydrazine group, a carboxyl group, a methylol groupand an active methylene group. Vinylsulfonic acid, acid anhydride,cyanoacrylate derivatives, melamine, etherified methylol, ester andurethane, and metal alkoxides such as tetramethoxysilane can also beused as monomers to introduce a crosslinking structure. Functionalgroups showing a crosslinking property as a result of decompositionreaction may be used as a block isocyanate group. That is to say,crosslinkable functional groups in the invention may be those notshowing reaction immediately but showing reactivity as a result ofdecomposition. The binders containing these crosslinkable functionalgroups can form a crosslinking structure by heating after coating.

It is also preferred for a light transmitting resin to be formed by theaddition of at least one of a monomer having a high refractive index andhyperfine particles of a metal oxide in addition to the binder polymerfor the purpose of the adjustment of the refractive index. Hyperfineparticles of metal oxides are preferably used from the point of theimprovement of hardness. The examples of high refractive index monomersinclude bis(4-methacryloylthiophenyl) sulfide, vinylnaphthalene,vinylphenyl sulfide, and 4-methacryloxyphenyl-4′-methoxyphenylthioether. As the examples of the hyperfine particles of metal oxides,hyperfine particles of oxides containing at least one kind of a metalselected from Si, Al, Zr, Zn, Ti, In, Sb and Sn are preferred, andspecifically SiO₂, ZrO₂, TiO₂, Al₂O₃, In₂O₃, ZnO, SnO₂, Sb₂O₃ and ITOare exemplified. Of these metal oxides, ZrO₂ is especially preferablyused. The addition amount of the high refractive index monomers ispreferably from 10 to 90 mass % of all the mass of the lighttransmitting resin, and more preferably from 20 to 80 mass %. Theaddition amount of the hyperfine particles of metal oxides is preferablyfrom 0 to 50 mass parts per 100 mass parts of the light transmittingresin, more preferably from 0 to 45 mass parts, and especiallypreferably from 0 to 40 mass parts. When the content of the hyperfineparticles of metal oxides is greater than 50 mass parts per 100 massparts of the light transmitting resin, the resulting film strength tendsto weaken.

When a light transmitting resin and a transparent substrate film arebrought into contact, the solvent in a coating solution for forming alight transmitting resin preferably consists of at least one or moresolvents capable of dissolving the transparent substrate film (e.g., atriacetyl cellulose support) and at least one or more solvents notcapable of dissolving the transparent substrate film for the purpose ofthe compatibility of revelation of an antiglare property and closeadhesion of the support (the transparent substrate film) and the lightscattering layer. More preferably, the boiling point of at least onesolvent of the solvents not dissolving the transparent substrate film ishigher than the boiling point of at least one solvent of the solventscapable of dissolving the transparent substrate film. Still morepreferably, the difference in temperature of the boiling point betweenthe solvent having the highest boiling point of the solvents notdissolving the transparent substrate film and the solvent having thehighest boiling point of the solvents capable of dissolving thetransparent substrate film is 30° C. or higher, and most preferably 50°C. or higher.

As the solvents capable of dissolving the transparent substrate film,describing the case of using cellulose acetate as the transparentsubstrate film as an example, ethers having from 3 to 12 carbon atoms,specifically dibutyl ether, dimethoxymethane, dimethoxyethane,diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolan,1,3,5-trioxane, tetrahydrofuran, anisole, and phenetole; ketones havingfrom 3 to 12 carbon atoms, specifically acetone, methyl ethyl ketone,diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone,cyclohexanone, methylcyclohexanone, and methylcyclohexanone; estershaving from 3 to 12 carbon atoms; specifically ethyl formate, propylformate, n-pentyl formate, methyl acetate, ethyl acetate, methylpropionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone; andorganic solvents having two or more kinds of functional groups,specifically 2-methoxymethyl acetate, 2-ethoxymethyl acetate,2-ethoxyethyl acetate, 2-ethoxyethyl propionate, 2-methoxyethanol,2-propoxyetanol, 2-butoxyethanol, 1,2-diacetoxyacetone, acetylacetone,diacetone alcohol, methyl acetoacetate, and ethyl acetoacetate areexemplified. These solvents can be used by one kind alone, or two ormore kinds in combination. As the solvents for dissolving thetransparent substrate film, ketone series solvents are preferably used.

As the solvents not dissolving the transparent substrate film,describing the case of using cellulose acetate as the transparentsubstrate film as an example, methanol, ethanol, 1-propanol, 2-propanol,1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol,cyclohexanol, isobutyl acetate, methyl isobutyl ketone, 2-octanone,2-pentanone, 2-hexanone, 2-heptanone, 3-pentanone, 3-haptanone,4-heptanone and toluene are exemplified. These solvents can be used byone kind alone, or two or more kinds in combination.

The above are described taking the case of using cellulose acetate asthe transparent substrate film as an example, the solvents to be usedare different according to the substrates. Further, when a transparentsubstrate film that is difficultly dissolved in a solvent is used, it isalso preferred to form an easily adhering layer on the substrate andthen form a light scattering layer on the easily adhering layer.

The proportion in mass of the total amount of the solvents capable ofdissolving the transparent substrate film (A) and the total amount ofthe solvents not dissolving the transparent substrate film (B) [(A)/(B)]is preferably from 5/95 to 50/50, more preferably from 10/90 to 40/60,and still more preferably from 15/85 to 30/70.

The ionizing radiation-curable resin compositions as described above canbe cured by the above-described ordinary curing methods of the ionizingradiation-curable resin compositions, that is, irradiation with electronbeams or ultraviolet rays.

For example, in the case of curing with electron beams, electron beamshaving energies of from 50 to 1,000 keV, preferably from 100 to 300 keV,emitted from various kinds of electron beam accelerators such as aCockcrost Walton type, a Van de Graaff type, a resonance transformertype, an insulating core transformer type, a linear type, a Dynamitrontype, and a high frequency type are used, and in the case of curing withultraviolet rays, ultraviolet rays emitted from light of rays such as asuper-high pressure mercury lamp, a high pressure mercury lamp, a lowpressure mercury lamp, a carbon arc, a xenon arc, and a metal halidelamp can be used.

When the light scattering film for use in the invention is used on theoutermost surface of the display, it is preferred to have a hard coatproperty. By possessing a hard coat property, it is not necessary toprovide a light scattering layer and a hard coat layer separately in twolayers, so that the invention is excellent in productivity andmanufacturing costs, which is one advantage of the invention. Thehardness of the light scattering layer is preferably H or higher in thepencil hardness test, more preferably 2H or higher and most preferably3H or higher.

Further, in the taper test in conformity with JIS K5400, the abrasionloss of a test piece before and after the test is preferably thesmaller.

When the light scattering film for use in the invention is used on theoutermost surface of the display, the surface unevenness is alsoimportant. Although it is possible to provide unevenness to give anantiglare property to the surface and obscure mirroring in to thedisplay surface, it is more preferred not to have surface unevenness forthe improvement of contrast, and center line average roughness Ra ispreferably in the range of from 0.003 to 0.20 μm, more preferably in therange of from 0.005 to 0.15 μm, and still more preferably in the rangeof from 0.005 to 0.10 μm. When Ra exceeds 0.20 μm, there tend to ariseproblems of the occurrence of whitening of the surface and a blur ofletters at the time when outer light is reflected.

The hardness and surface unevenness described above can be preferablyapplied to the later-described antireflection film comprising a lightscattering layer having provided a low refractive index layer on thesurface thereof.

A Low Refractive Index Layer:

When the light scattering film for use in the invention is used on thesurface of the organic EL display, a low refractive index layer can beprovided on the outside of the light scattering layer, that is, thefarther side from the transparent substrate film. By possessing the lowrefractive index layer, an antireflection property is given to the lightscattering film, and mirroring in onto the surface of the display can beprevented, so that the improvement of contrast becomes possible. It ispreferred to set the refractive index of the low refractive index layerlower than that of the light scattering layer. When the difference inthe refractive index between the low refractive index layer and thelight scattering layer is too small, an antiglare property lowers, whilewhen the difference is too large, the tint of reflected light is liableto be stronger. The difference in the refractive index between the lowrefractive index layer and the light scattering layer is preferably 0.01or more and 0.30 or less, and more preferably 0.05 or more and 0.20 orless.

The low refractive index layer can be formed using materials of lowrefractive index. As the materials of low refractive index, lowrefractive index binders can be used. It is also possible to form thelow refractive index layer by adding the particles to the binders.

The composition for forming the low refractive index layer can containthe later-described organosilane compounds.

The low refractive index binder can preferably contain afluorine-containing copolymer. It is preferred for thefluorine-containing copolymer to contain a structural unit derived froma fluorine-containing vinyl monomer and a structural unit to impart acrosslinking property.

Fluorine-Containing Copolymer:

As the fluorine-containing vinyl monomers mainly constitutingfluorine-containing copolymers, fluoroolefins (e.g., fluoroethylene,vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, etc.),partially or completely fluorinated alkyl ester derivatives of(meth)acrylic acid (e.g., Viscoat 6FM (trade name), manufactured byOsaka Organic Chemical Industry Ltd., R-2020 (trade name), manufacturedby Daikin Industries Ltd., etc.), and completely or partiallyfluorinated vinyl ethers are exemplified. The preferred areperfluoroolefins, and the especially preferred is hexafluoropropylenefrom the points of refractive index, solubility, transparency and easyavailability.

The refractive index can be lowered by the increase of the compositionalratio of the fluorine-containing vinyl monomer, but the film strength isliable to decrease on the other hand. It is preferred in the inventionto introduce the fluorine-containing vinyl monomers so that the fluorinecontent in the fluorine-containing copolymer is from 20 to 60 mass %,more preferably from 25 to 55 mass %, and especially preferably from 30to 50 mass %.

As the constitutional units for giving crosslinking reactivity, theunits shown by the following (A), (B) and (C) are mainly exemplified.

-   (A) Constitutional units obtained by polymerization of monomers    having self-crosslinking functional groups in the molecule in    advance such as glycidyl (meth)acrylate and glycidyl vinyl ether;-   (B) Constitutional units obtained by polymerization of monomers    having a carboxyl group, a hydroxyl group, an amino group, or a    sulfo group (e.g., (meth)acrylic acid, methylol (meth)acrylate,    hydroxyalkyl (meth)acrylate, allyl acrylate, hydroxyethyl vinyl    ether, hydroxybutyl vinyl ether, maleic acid, crotonic acid, etc.);    and-   (C) Constitutional units capable of obtaining by reaction of a    compound having functional groups reactive with functional    groups (A) and (U) and crosslinking functional groups different from    the above groups in the molecule with constitutional units (A)    and (R) (e.g., constitutional units capable of synthesizing by a    method of acting acrylic acid chloride to a hydroxyl group); are    exemplified.

The above constitutional units (C) preferably have a photo-polymerizablegroup as the crosslinkable functional group. As the photo-polymerizablegroups, e.g., a (meth)acryloyl group, an alkenyl group, a cinnamoylgroup, a cinnamylideneacetyl group, a benzalacetophenone group, astyrylpyridine group, an α-phenylmaleimido group, a phenyl azide group,a sulfonyl azide group, a carbonyl azide group, a diazo group, ano-quinonediazide group, a furylacryloyl group, a coumarin group, apyrone group, an anthracene group, a benzophenone group, a stilbenegroup, a dithiocarbamate group, a xanthate group, a 1,2,3-thiadiazolegroup, a cyclopropene group, and an azadioxabicyclo group can beexemplified. These groups may be used not only by one kind alone butalso two or more groups in combination. Of these groups, a(meth)acryloyl group and a cinnamoyl group are preferred, and a(meth)acryloyl group is especially preferred.

As specific methods for preparing photo-polymerizable group-containingcopolymers, the following methods can be exemplified, but the inventionis not restricted to these methods.

(a) A method of esterification by reacting a crosslinkable functionalgroup-containing copolymer containing a hydroxyl group with(meth)acrylic acid chloride;

(b) A method of making urethane by reacting a crosslinkable functionalgroup-containing copolymer containing a hydroxyl group with(meth)acrylate containing an isocyanate group;

(c) A method of esterification by reacting a crosslinkable functionalgroup-containing copolymer containing an epoxy group with (meth)acrylicacid; and

(d) A method of esterification by reacting a crosslinkable functionalgroup-containing copolymer containing a carboxyl group with(meth)acrylate containing an epoxy group.

Incidentally, the amount of photo-polymerizable groups to be introducedcan be arbitrarily adjusted and a carboxyl group and a hydroxyl groupmay be left from the points of stability of film surface, reduction ofsurface failure in the coexistence of inorganic particles, andimprovement of film strength.

In the invention, the amount of constitutional unit to be introduced forthe purpose of giving a crosslinking property in a fluorine-containingcopolymer is preferably from 10 to 50 mol %, more preferably from 15 to45 mol %, and especially preferably from 20 to 40 mol %.

In copolymers useful for the low refractive index layer in theinvention, besides the repeating units derived from thefluorine-containing vinyl monomers and repeating units having a(meth)acryloyl group on the side chain of the constitutional unit forimparting a crosslinking property, other vinyl monomers can becopolymerized arbitrarily from various points such as adhesion to thesubstrate, Tg of the polymer (contributing to the film thickness),solubility in solvents, transparency, a sliding property, dust proof andantifouling properties. These vinyl monomers may be used in combinationof two or more according to purposes. These vinyl monomers arepreferably contained in the range of from 0 to 65 mol % in total in thecopolymer, more preferably in the range of from 0 to 40 mol %, andespecially preferably in the range of from 0 to 30 mol %.

The vinyl monomer units usable in combination are not especiallyrestricted, and, for example, olefins (e.g., ethylene, propylene,isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic acidesters (e.g., methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate,2-hydroxyethyl acrylate), methacrylic acid esters (e.g., methylmethacrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethylmethacrylate, etc.), styrene derivatives (e.g., styrene,p-hydroxymethylstyrene, p-methoxystyrene, etc.), vinyl ethers (e.g.,methyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether,hydroxyethyl vinyl ether, hydroxybutyl vinyl ether. etc.), vinyl esters(e.g., vinyl acetate, vinyl propionate, vinyl cinnamate, etc.),unsaturated carboxylic acids (acrylic acid, methacrylic acid, crotonicacid, maleic acid, itaconic acid, etc.), acrylamides (e.g.,N,N-dimethylacrylamide, N-t-butylacrylamide, N-cyclohexylacrylamide,etc.), and methacrylamides (e.g., N,N-dimethylmethacrylamide,acrylonitrile, etc.) can be exemplified.

Especially useful fluorine-containing copolymers in the invention arerandom copolymers of perfluoroolefin and vinyl ethers or vinyl esters.It is particularly preferred to have a group capable of crosslinkingsingly (radical reactive groups such as a (meth)acryloyl group, ringopening polymerizable groups such as an epoxy group, an oxetanyl group,etc.). These polymerization units containing the crosslinking reactivegroup preferably account for from 5 to 70 mol % of all thepolymerization units of the polymer, and especially preferably from 30to 60 mol %. As preferred polymers, those disclosed in JP-A-2002-243907,JP-A-2002-372601, JP-A-2003-26732. JP-A-2003-222702, JP-A-2003-294911,JP-A-2003-329804, JP-A-2004-4444, and JP-A-2004-45462 can beexemplified.

It is preferred that a polysiloxane structure is introduced into thefluorine-containing copolymers useful in the invention for the purposeof giving an antifouling property. The introducing methods of apolysiloxane structure are not restricted. For example, a method ofintroducing a polysiloxane block copolymer component by using a siliconemacro-azo initiator as disclosed in JP-A-6-93100, JP-A-11-189621,JP-A-11-228631, and JP-A-2000-313709, and a method of introducing apolysiloxane graft copolymer component by using a silicone macromer asdisclosed in JP-A-2-251555 and JP-A-2-308806 are preferred. Asespecially preferred compounds, the polymers disclosed in Examples 1, 2and 3 in JP-A-11-189621, and Copolymers A-2 and A-3 disclosed inJP-A-2-251555 can be exemplified. It is preferred that thesepolysiloxane components account for from 0.5 to 10 mass % of thepolymer, and especially preferably from 1 to 5 mass %.

The preferred molecular weight of the fluorine-containing copolymerspreferably used In the invention is 5,000 or more as mass averagemolecular weights preferably from 10,000 to 500,000, and most preferablyfrom 15,000 to 200,000. By using polymers different in average molecularweights, the state of film surface and scratch resistance can also beimproved.

A hardening agent having a polymerizable unsaturated group may bearbitrarily used in these fluorine-containing copolymers as disclosed inJP-A-10-25388 and JP-A-2000-17028. As disclosed in JP-A-2002-145952, itis also preferred to use in combination of a compound having afluorine-containing polyfunctional polymerizable unsaturated group. Asthe examples of the compounds having a polyfunctional polymerizableunsaturated group, the polyfunctional monomers described in the abovelight scattering layer can be exemplified. These compounds have a greateffect of the improvement of scratch resistance particularly when acompound having a polymerizable unsaturated group is used in thecopolymer main body.

The refractive index of the low refractive index layer is preferablyfrom 1.20 to 1.46, more preferably from 1.25 to 1.42, and especiallypreferably from 1.30 to 1.38. The thickness of the low refractive indexlayer is preferably from 50 to 150 nm, and more preferably from 70 to120 nm.

Fine Particles:

Fine particles preferably usable in the low refractive index layer inthe invention will be described below.

The coating weight of the fine particles contained in the low refractiveindex layer is preferably from 1 to 100 mg/m², more preferably from 5 to80 mg/m², and still more preferably from 1 to 70 mg/m². When the coatingweight of the fine particles is more than the greatest lower bound, animproving effect of scratch resistance is apparently revealed, and whenless than the least upper bound, minute irregularities are formed on thesurface of the low refractive index layer, so that unfavorable statessuch as deteriorations in appearance and integrated reflectance do notoccur and preferred. Since the fine particles are contained in the lowrefractive index layer, the refractive index is preferably low.

Specifically, fine particles contained in the low refractive index layerare inorganic fine particles, hollow inorganic fine particles, or holloworganic fine particles, and they are preferably low in refractive index.Hollow inorganic fine particles are especially preferred. As theinorganic fine particles, e.g., silica fine particles and hollow silicafine particles are exemplified. The average particle size of these fineparticles is preferably 30% or more and 100% or less of the thickness ofthe low refractive index layer, more preferably 30% or more and 80% orless, and still more preferably 35% or more and 70% or less. That is,when the thickness of the low refractive index layer is 100 nm, theparticle size of the fine particles is preferably 30 nm or more and 100nm or less, more preferably 30 nm or more and 80 nm or less, and stillmore preferably 35 nm or more and 70 nm or less.

For contriving strengthening of scratch resistance, it is preferred thatinorganic particles arc contained in all the layers of the antiglarefilm, and most preferably silica particles are contained in all thelayers of the antiglare film.

The improving effect of scratch resistance of the (hollow) silica fineparticles is revealed when the particle size is greater than thegreatest lower bound, and when less than the least upper bound, minuteirregularities are formed on the surface of the low refractive indexlayer, so that unfavorable states such as deteriorations in appearanceand integrated reflectance do not occur and preferred.

(Hollow) silica particles may be crystalline or amorphous, and may bemonodisperse particles or agglomerated particles (in this case secondaryparticle size is preferably from 15 to 150% of the layer thickness ofthe low refractive index layer). Further, a plurality of two or moreparticles (in kinds or particle sizes) may be used. The shape of theparticles is most preferably spherical, but may be amorphous.

For lowering the refractive index of the low refractive index layer, itis especially preferred to use hollow silica fine particles. Therefractive index of the hollow silica fine particles is from 1.17 to1.40, more preferably from 1.17 to 1.35, and still more preferably from1.17 to 1.32. The refractive index here is the refractive index of theparticles at large and not means the refractive index of the silica ofthe shell forming the hollow silica particles alone. At this time, voidratio x is computed from the following equation (1) taking the radius ofthe void in the particle as r_(i), and the radius of the shell of theparticle as r₀:x=(4πr_(i) ³/3)/(4πr₀ ³/3)×100  (1)

Void ratio x is preferably from 10 to 60%, more preferably from 20 to60%, and most preferably from 30 to 60%. To make the refractive index ofthe hollow silica particles lower and make the void ratio greater resultin thinning of the thickness of the shell and weakening of the strengthof the particles. From the viewpoint of scratch resistance, particles ofa low refractive index of less than 1.17 are difficult to be used. Therefractive index of the hollow silica particles can be measured withAbbe's refractometer (manufactured by Atago Co., Ltd.).

In the invention, from the aspect of the improvement of an antifoulingproperty, it is preferred to further lower the surface free energy ofthe surface of the low refractive index layer. Specifically, fluorinecompounds and compounds having a polysiloxane structure are preferablyused in the low refractive index layer.

As the additives having a polysiloxane structure, reactivegroup-containing polysiloxane (e.g., “KF-100T”, “X-22-169AS”, “K-102”,“X-22-3701IE”, “X-22-164B”, “X-22-5002”, “X-22-173B”, “X-22-174D”,“X-22-167B”, and “X-22-161AS” (trade names, manufactured by Shin-EtsuChemical Co., Ltd.), “AK-5”, “AK-30” and “AK-32” (trade names,manufactured by TOAGOSEI CO., LTD.), “Silaplane FM0725” and “SilaplaneFM0721” (trade names, manufactured by Chisso Corporation)) are alsopreferably added. Further, silicone compounds shown in Tables 2 and 3 inJP-A-2003-112383 can also be preferably used.

As the fluorine compounds, compounds having a fluoroalkyl group arepreferably used. The fluoroalkyl group preferably has from 1 to 20carbon atoms, more preferably from 1 to 10 carbon atoms, may have astraight chain structure (e.g., —CF₂CF₃, —CH₂(CF₂)₄H, —CH₂(CF₂)₈CF₃,—CH₂CH₂(CF₂)₄H, etc.), may have a branched structure (e.g., CH(CF₃)₂,CH₂CF(CF₃)₂, CH(CH₃)CF₂CF₃, CH(CH₃)(CF₂)₅CF₂H, etc.), may have analicyclic structure preferably a 5- or 6-membered ring, e.g., aperfluorocyclohexyl group, a perfluorocyclopentyl group, or an alkylgroup substituted with these groups), or may have an ether bond (e.g.,CH₂OCH₂CF₂CF₃, CH₂CH₂OCH₂C₄F₈H, CH₂CH₂OCH₂CH₂C₈F₁₇,CH₂CH₂OCF₂CF₂OCF₂CF₂H, etc.). A plurality of the fluoroalkyl groups maybe contained in the same molecule.

It is preferred for the fluorine compounds to have substituentscontributing to forming a bond to or compatibility with a low refractiveindex layer film, and it is preferred to have a plurality ofsubstituents, and the substituents may be the same or different. Theexamples of preferred substituents include an acryloyl group, amethacryloyl group, a vinyl group, an aryl group, a cinnamoyl group, anepoxy group, an oxetanyl group, a hydroxyl group, a polyoxyalkylenegroup, a carboxyl group, and an amino group. The fluorine compounds maybe polymers or oligomers with compounds not containing a fluorine atom,and the molecular weight is not especially restricted. The content offluorine atoms in the fluorine compounds is not especially restricted,but preferably 20 mass % or more, especially preferably from 30 to 70mass %, and most preferably from 40 to 70 mass %. As the examples ofpreferred fluorine compounds, R-2020, M-2020, R-3833, M-3833, and OPTOOLDAC (trade names, manufactured by Daikin Industries Ltd.), MegafacF-171, F-172, F-179A, DEFENSA MCF-300, and MCF-322 (trade names,manufactured by Dainippon Ink and Chemicals Inc.) are exemplified, butfluorine compounds are not restricted thereto. These fluorine compoundsand compounds having a polysiloxane structure are preferably added inthe range of from 0.1 to 10 mass % of all the solids content of the lowrefractive index layer, and especially preferably from 1 to 5 mass %.

A High Refractive Index Layer and an Intermediate Refractive IndexLayer:

An antireflection property of the antireflection film in the inventioncan be heightened by providing a high refractive index layer between thetransparent support of the light scattering layer and the low refractiveindex layer on the opposite side to make use of optical interferencetogether with the low refractive index layer. Further, it is preferredto provide between the light scattering layer and the high refractiveindex layer an intermediate refractive index layer having a refractiveindex that is intermediate of the refractive indexes of the lightscattering layer and the high refractive index layer.

In the specification of the invention hereafter, the high refractiveindex layer and the intermediate refractive index layer are sometimesgenerically referred to as a high refractive index layer. Incidentally,in the invention, “high”, “intermediate” and “low” of the highrefractive index layer, intermediate refractive index layer and lowrefractive index layer mean the relative small and great values of therefractive indexes among the layers. Further, describing therelationships with the transparent support, it is preferred that therefractive indexes satisfy the relationships of a transparent support>alow refractive index layer, a high refractive index layer>a transparentsupport.

Further, in the specification of the invention, a high refractive indexlayer, an intermediate refractive index layer and a low refractive indexlayer are sometimes generically referred to as an antireflection layer.

For manufacturing an antireflection film by forming a low refractiveindex layer on a high refractive index layer, the refractive index ofthe high refractive index layer is preferably from 1.55 to 2.40, morepreferably from 1.60 to 2.20, and still more preferably from 1.60 to2.00.

When an antireflection film is formed by coating an intermediaterefractive index layer, a high refractive index layer, and a lowrefractive index layer in order nearer from the support, the refractiveindex of the high refractive index layer is preferably from 1.65 to2.40, and more preferably from 1.70 to 2.20. The refractive index of theintermediate refractive index layer is adjusted so that the value isintermediate between the refractive index of the low refractive indexlayer and the refractive index of the high refractive index layer. Therefractive index of the intermediate refractive index layer ispreferably from 1.55 to 1.80, and mote preferably from 1.55 to 1.70.

The specific examples of inorganic particles for use in the highrefractive index layer and the intermediate refractive index layer arepreferably inorganic particles primarily comprising inorganic oxides,e.g., TiO₂ ZrO₂, Al₂O₃, In₂O₃, ZnO, SnO₂, Sb₂O₃, ITO, etc. Inorganicparticles mainly comprising SiO₂ can also be used for the adjustment ofthe refractive index. For use in the high refractive index layer, TiO₂and ZrO₂ are especially preferred to increase a refractive index. It isalso preferred for the surfaces of inorganic fillers to be treated witha silane coupling agent or a titanium coupling agent, and surfacetreating agents having a functional group capable of reacting with thebinder on the surface are preferably used.

The content of the inorganic particles in the high refractive indexlayer is preferably from 10 to 90 mass % of the mass of the highrefractive index layer, more preferably from 15 to 80 mass %, andespecially preferably from 15 to 75 mass %. Two or more kinds ofinorganic particles can be used in combination in high refractive indexlayer.

When a low refractive index layer is formed on a high refractive indexlayer, the refractive index of the high refractive index layer ispreferably higher than the refractive index of the transparent support.

The lower the reflectance of the antireflection film, the more preferredis the reduction of mirroring in or the improvement of contrast. Theaverage value of the reflectance in the wavelength region of from 450 to650 nm of mirror reflectivity in the incidence of 5° is preferably 0.1to 2.0%, more preferably from 0.1 to 1.2%, and especially preferablyfrom 0.1 to 0.6%. When the average value exceeds 2.0%, the effects ofthe reduction of mirroring in and the improvement of contrast arelittle, so that not preferred.

Since the antireflection film prevents reflection in a specificwavelength region by making use of thin film interference of one or morelayers, there is a problem of reflected tint. The tints of regularlyreflected light of the antireflection film to 5° incident light of CIEstandard light source D65 in the wavelength region of from 380 to 780 nmas a* and b* values of CIE1976L*a*b* color space are respectivelypreferably in the range of −8≦a*≦8 and −10≦b*≦10, more preferably −5≦a*5and −6≦b*≦6, especially preferably 0≦a*≦5 and −6≦b*≦0, and still furtherpreferably 0≦a*≦3 and −4≦b*≦0. When these values exceed the above rangesrespectively, reflected colors are conspicuous especially in blackdisplay, so that not preferred.

Besides the above layers, it is preferred that various functional groupsare provided on the light scattering film for use in the invention. Asthe examples of the functional layers, a conductive layer, an easilyadhesive layer and an absorptive layer are exemplified.

Forming of Layers:

The light scattering layer for use in the invention, and according tonecessity, a low refractive index layer, a high/intermediate refractiveindex layer, or other layers are formed by coating a coating solution ona transparent support, heating, drying, and after that, if necessary,irradiating light and/or heating to harden the monomer and the curableresin for forming each layer.

The coating methods of each layer of the light scattering film in theinvention are not especially restricted, but a dip coating method, anair knife coating method, a curtain coating method, a roller coatingmethod, a wire bar coating method, a gravure coating method, anextrusion coating method (a die coating method) (refer to U.S. Pat. No.2,681,294), and a micro-gravure coating method are used. Of thesemethods, a micro-gravure coating method and a die coating method arepreferably used for high productivity and coating uniformity.

Further, for the purpose of the improvement of adhesion of thetransparent substrate film and covering layers, one or both surfaces ofthe transparent substrate film can also be subjected to pretreatmentsuch as hydrophilization treatment or treatment to make irregularities.As the pretreatments, corona discharge treatment, glow dischargetreatment, chromic acid treatment (a wet type), saponification treatment(a wet type), flame treatment, hot air treatment, and ozone-UVirradiation treatment are exemplified, and corona discharge treatment,glow discharge treatment and saponification treatment (a wet type) areespecially preferred.

Transparent Substrate Film:

As the materials of transparent substrate film 20, there are atransparent resin film, a transparent resin plate, and a transparentresin sheet. As the transparent resin films, films comprising celluloseacylates (e.g., a triacetyl cellulose (TAC) film (refractive index:1.48)), polyethylene terephthalate (PET) films, polyethylene naphthalate(PEN) films, diacetylene cellulose films, acetate butyrate cellulosefilms, polyether sulfone films, polyacrylic resin films, polyurethaneresin films, polyester films, polycarbonate films, polysulfone films,polyether films, polymethylpentene films, polyether ketone films,(meth)acrylonitrile films, cycloolefin films, and films comprising apolymer having a lactone ring can be used. The thickness of thetransparent substrate film is generally preferably from 10 to 80 ρm, andmore preferably from 20 to 60 μm. In the invention, the thickness ispreferably the thinner for the reduction of a blur of letters due tolight scattering, but when the thickness is thinner than 10 μm, the filmstrength decreases, so that not preferred.

Organic Electroluminescent Display:

The organic electroluminescent display in the invention is a displaycomprising a pair of electrodes of the anode and the cathode and alight-emitting layer or a plurality of thin films of organic compoundsincluding a light-emitting layer between the pair of electrodes, and thedisplay may have a hole injecting layer, a hole transporting layer, anelectron injecting layer, an electron transporting layer, and aprotective layer besides the light-emitting layer, and each of theselayers may have other function. Each layer can be formed with variouskinds of materials.

The anode is to supply positive holes to a hole injecting layer, a holetransporting layer and a light-emitting layer, and metals, alloys, metaloxides, electrically conductive compounds, and mixtures of thesematerials can be used as the materials, and preferred materials arematerials having a work function of 4 eV or more. The specific examplesof the materials of the anode include electrically conductive metaloxides, e.g., tin oxide, zinc oxide, indium oxide, indium tin oxide(ITO), etc., metals, e.g., gold, silver, chromium, nickel, etc.,mixtures or laminates of these metals with electrically conductive metaloxides, inorganic electrically conductive substances, e.g., copperiodide, copper sulfide, etc., organic electrically conductive materials,e.g., polyaniline, polythiophene, polypyrrole, etc., laminates of thesematerials with ITO, etc. Of these materials, electrically conductivemetal oxides are preferred, and ITO is especially preferred in view ofproductivity, high conductivity, transparency and the like. The filmthickness of the anode can be arbitrarily selected dependent uponmaterials, but generally it is preferably in the range of from 10 nm to5 μm, more preferably from 50 nm to 1 μm, and still more preferably from100 nm to 500 nm.

The substrate is not especially restricted, but a transparent ortranslucent substrate is preferably used, and generally the anode isformed on a substrate such as soda-lime glass, non-alkali glass, or atransparent resin. When glass is used, it is preferred to use non-alkaliglass to lessen elution of ions from the glass. Further, when soda-limeglass is used, those having barrier coat of silica and the like arepreferably used.

The thickness of the substrate is not especially restricted so long asthe thickness is sufficient to maintain mechanical strength, but in thecase where a light scattering film is used on the surface of the displayas in the invention, when the thickness of the substrate on the viewingside is thick, a blur of letters is liable to occur, and the thicknessof the substrate is preferably the thinner. The thickness of thesubstrate on the viewing side is preferably from 0.01 to 0.70 mm, morepreferably from 0.02 to 0.50 mm, and especially preferably from 0.03 to0.30 mm.

In the invention, for the compatibility of the improvement of viewingangle dependency and the reduction of a blur of letters, and in thepoints of the strength and the duration of life of the display, to use athin substrate preferably glass) of from 0.03 to 0.30 mm on the viewingside can be said to be a most preferred mode. When a substrate isthinner than 0.30 μm, it is more preferred to coat a polymer on at leastone of one-side surface and edge of the substrate.

For the reduction of a blur of letters, for example, it is alsopreferred to use a gas barrier film in place of a glass substrate as atleast a substrate on a viewing side. The gas barrier film is a filmcomprising a plastic support provided with a gas-impermeable barrierlayer. As the examples of the gas barrier films, the films vacuumevaporated with silicon oxide or aluminum oxide (JP-B-53-12953 (the term“JP-B” as used herein refers to an “examined Japanese patentpublication”) and JP-A-58-217344), the films having an organic andinorganic hybrid coating layer (JP-A-2000-323273 and JP-A-2004-25732),the films containing an inorganic laminar compound (JP-A-2001-205743),the films of laminates of inorganic materials (JP-A-2003-206361 andJP-A-2006-263989), the films of laminates of organic layer and inorganiclayer alternately (JP-A-2007-30387, U.S. Pat. No. 6,413,645, Affinito etal., Thin Solid Films, pp. 290-291 (1996)), and the films of laminatesof organic layer and inorganic layer continuously (U.S. Patent2004-46,497) are exemplified. As the barrier property of the gas barrierfilm, water vapor permeability at 40° C. 90% RH is preferably 0.01g/m²·day or less, and more preferably 0.001 g/m²·day or less.

The light scattering film can also be used by being stuck on the gasbarrier film with an adhesive and the like.

As another embodiment of the invention, the light scattering filmincludes a gas barrier film and a light scattering layer directly formedon the gas barrier film, and the scattering film is used as at least asubstrate on the viewing side for example in place of glass. This modehas the advantage that the improvement of viewing angle dependency andthe reduction of a blur of letters can be reconciled and the film can belightweight and thin-typed film.

Various methods are used in the manufacture of the anode dependent uponmaterials. For example, in the case of ITO, a film is formed accordingto an electron beam method, a sputtering method, a resistance heatingvacuum evaporation method, a chemical reaction method (a sol-gel methodand the like), or a method of coating the dispersion of indium tinoxide. The anode can lower driving voltage of a display or can increaseemission efficiency by washing and other treatments. In the case of ITO,for example, UV-ozone treatment is effective.

The cathode is to supply electrons to an electron injecting layer, anelectron transporting layer, and a light-emitting layer, and is selectedby considering the adhesion with the layers contiguous to the negativeelectrode such as the electron injecting layer, electron transportinglayer, and light-emitting layer, ionization potential and stability. Asthe materials of the cathode, metals, alloys, metal oxides, electricallyconductive compounds, and mixtures of these materials can be used. Asthe specific examples of the materials of the cathode, alkali metals(e.g., Li, Na, K, etc.) and fluorides thereof, alkaline earth metals(e.g., Mg, Ca, etc.) and fluorides thereof, gold, silver, lead,aluminum, sodium-potassium alloys and mixed metals thereof,lithium-aluminum alloys and mixed metals thereof, magnesium-silveralloys and mixed metals thereof, and rare earth metals such as indiumand ytterbium are exemplified, and preferred materials are materialshaving a work function of 4 eV or less. More preferred materials arealuminum, lithium-aluminum alloys and mixed metals thereof, andmagnesium-silver alloys and mixed metals thereof. The film thickness ofthe cathode can be arbitrarily selected dependent upon materials, butgenerally it is preferably in the range of from 10 nm to 5 μm, morepreferably from 50 nm to 1 μm, and still more preferably from 100 nm to1 μm. An electron beam method, a sputtering method, a resistance heatingvacuum evaporation method, and a coating method are used in themanufacture of the cathode, and simple substance of a metal can beevaporated or two or more components can be evaporated at the same time.Further, a plurality of metals may be evaporated at the same time toform an alloy electrode, or an alloy prepared in advance may beevaporated.

The sheet resistance of the anode and cathode is preferably low, forexample, several hundreds Ω/□ or less is preferred.

The barrier film may be stuck on the cathode to prevent gas frominvading and form a protective layer on the surface of the display.

Any material can be used as the materials of the light-emitting layer solong as the material is capable of forming a layer having functions ofinjecting positive holes from the anode, the hole injecting layer, orthe hole transporting layer and at the same time injecting electronsfrom the cathode, the electron injecting layer, or the electrontransporting layer when electric field is applied, function oftransferring injected charges, and function of enabling light emissionby offering a site for recombination of the holes and the electrons.Preferably for the light-emitting layer to contain the compound of theinvention, but light-emitting materials other than the compound of theinvention can also be used. The examples of other compounds includevarious metal complexes represented by metal complexes or rare earthcomplexes of benzoxazole derivatives, benzimidazole derivatives,benzothiazole derivatives, styrylbenzene derivatives, polyphenylderivatives, diphenylbutadiene derivatives, tetraphenylbutadienederivatives, naphthalimide derivatives, coumarin derivatives, perylenederivatives, perinone derivatives, oxadiazole derivatives, aldazinederivatives, pyraridine derivatives, cyclopentadiene derivatives,bisstyrylanthracene derivatives, quinacridone derivatives,pyrrolopyridine derivatives, thiadiazolopyridine derivatives,cyclopentadiene derivatives, styrylamine derivatives, aromaticdimethylidyne compounds, and 8-quinolinol derivatives, and polymercompounds such as polythiophene, polyphenylene, polyphenylenevinylene,etc. The film thickness of the light-emitting layer is not especiallyrestricted, but generally preferably the film thickness is in the rangeof from 1 nm to 5 μm, more preferably from 5 nm to 1 μm, and still morepreferably from 10 nm to 500 nm.

The forming method of the light-emitting layer is not especiallyrestricted, and a resistance heating vacuum evaporation method, anelectron beam method, a sputtering method, a molecular laminatingmethod, a coating method (e.g., spin coating, cast coating, dipcoating), and an LB method are used, and a resistance heating vacuumevaporation method and a coating method are preferably used.

The materials of the hole injecting layer and the hole transportinglayer are sufficient if they have any of the functions of injectingpositive holes from the anode, transporting positive holes, and blockingthe electrons injected from the cathode. The specific examples of thematerials include carbazole derivatives, triazole derivatives, oxazolederivatives, oxadiazole derivatives, imidazole derivatives,polyarylalkane derivatives, pyrazoline derivatives, pyrazolonederivatives, phenylenediamine derivatives, arylamine derivatives,amino-substituted chalcone derivatives, styrylanthracene derivatives,fluorenone derivatives, hydrazone derivatives, stilbene derivatives,silazane derivatives, aromatic tertiaryl amine compounds, styrylaminecompounds, aromatic dimethylidyne series compounds, porphyrin seriescompounds, polysilane series compounds, poly(N-vinylcarbazole)derivatives, aniline series copolymers, and electrically conductive highmolecular weight oligomers, such as thiophene oligomers andpolythiophene. The film thickness of the hole injecting layer and thehole transporting layer is not especially restricted, and generally itis preferably in the range of from 1 nm to 5 μm, more preferably from 5nm to 1 μm, and still more preferably from 10 nm to 500 nm. The holeinjecting layer and the hole transporting layer may have a single layerstructure of one kind or two or more kinds of the above materials, ormay be a multilayer structure comprising a plurality of layers havingthe same composition or different compositions.

As the forming method of the hole injecting layer and the holetransporting layer, a vacuum evaporation method, an LB method, a methodof dissolving or dispersing the above hole injecting and holetransporting materials in solvents and coating (spin coating, castcoating or dip coating) are used. In the case of a coating method, thehole injecting and hole transporting materials can be dissolved ordispersed with a resin component. The examples of the resin componentsinclude polyvinyl chloride, polycarbonate, polystyrene, polymethylmethacrylate, polybutyl methacrylate, polyester, polysulfone,polyphenylene oxide, polybutadiene, poly(N-vinylcarbazole), hydrocarbonresin, ketone resins phenoxy resin, polyamide, ethyl cellulose, vinylacetate, ABS resin, polyurethane, melamine resin, unsaturated polyesterresin, alkyd resin, epoxy resin, silicone resin, and the like.

Materials of the electron injecting layer and the electron transportinglayer are sufficient if they have any of the functions of injectingelectrons from the cathode, transporting electrons, and barriering offthe positive holes injected from the anode. The specific examples of thematerials include various metal complexes represented by metal complexesof triazole derivatives, oxazole derivatives, oxadiazole derivatives,fluorenone derivatives, anthraquinodimethane derivatives, anthronederivatives, diphenylquinone derivatives, thiopyrandioxide derivatives,carbodiimide derivatives, fluorenylidenemethane derivatives,distyrylpyrazine derivatives, heterocyclic tetracarboxylic acidanhydrides such as naphthalene and perylene, phthalocyanine derivatives,and 8-quinolinol derivatives, and metal complexes having a ligand suchas metallophthalocyanine, benzoxazole or benzothiazole. The filmthickness of the electron injecting layer and the electron transportinglayer is not especially restricted, but it is generally preferably from1 nm to 5 μm, more preferably from 5 nm to 1 μm, and still morepreferably from 10 nm to 500 nm. The electron injecting layer and theelectron transporting layer may be single layer structure comprising oneor two or more of the above materials, or may be a multilayer structurecomprising a plurality of layers having the same composition ordifferent compositions.

As the forming method of the electron injecting layer and the electrontransporting layer, a vacuum evaporation method, an LB method, a methodof dissolving or dispersing the above electron injecting and electrontransporting materials in solvents and coating (spin coating, castcoating or dip coating) are used. In the case of a coating method, theelectron injecting and electron transporting materials can be dissolvedor dispersed with a resin component. As the examples of the resincomponents include, for example, those exemplified in the positive holeinjecting and transporting layers can be applied.

The materials of the protective layer are sufficient if they have thefunction of preventing substances that accelerate deterioration of thedisplay, such as water or oxygen, from invading the display. Thespecific examples of the materials include metals such as In, Sn, Pb,Au, Cu, Ag, Al, Ml and Ni; metal oxides such as MgO, SiO, SiO₂, Al₂O₃,GeO, NiO, CaO, BaO, Fe₂O₃, Y₂O₃, and TiO₂; metal fluorides such as MgF₂,LiF, AlF₃, and CaF₂; polyethylene, polypropylene, polymethylmethacrylate, polyimide, polyurea, polytetrafluoroethylene,polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymers ofchlorotrifluoroethylene and dichlorodifluoroethylene, copolymersobtained by copolymerization of a monomer mixture of tetrafluoroethyleneand at least one comonomer, fluorine-containing copolymers having cyclicstructures on the main chain, water-absorbing substances having acoefficient of water absorption of 1% or more, and moisture-proofsubstances having a coefficient of water absorption of 0.1% or less.

The forming method of the protective layer is also not especiallyrestricted and, for example, a vacuum evaporation method, a sputteringmethod, a reactive sputtering method, an MBE (molecular beam epitaxy)method, a cluster ion beam method, an ion-plating method, a plasmapolymerization method (a high frequency exciting ion plating method), aplasma CVD method, a laser CVD method, a heat CVD method, a gas sourceCVD method, and a coating method can be used.

In the organic EL display, light collecting effect can be improved bythe photo-resonance of the lights reflected on the surface on thelight-emitting layer side of each electrode between both electrodes. Insuch a case, viewing angle dependency is especially liable to occur, sothat the effect of the invention is great. The effect of the inventionis especially great in the organic EL display wherein the maximum valueof emission wavelength is in the range of 350 nm or more and 700 nm orless, and [(x₆₀-x₀)²+(y₆₀-y₀)²]^(1/2) is in the range of 0.05 or moreand 0.3 or less, taking the color coordinate of emission spectrum in thedirection of output angle of 0° on xy chromaticity diagram as (x₀, y₀)and the color coordinate of emission spectrum in the direction of outputangle of 60° as (x₆₀, y₆₀), and the effect of the invention is stillfurther great in the organic EL display in the range of 0.1 or more and0.2 or less. When the value is too great, viewing angle characteristicsof the level that is a little unpleasant remains even by the invention,and when the value is too small, the effect of the invention tends to behardly obtained.

The organic EL display in the invention has the light scattering filmhaving the specific optical performances, so that the change in the tintis little when the image in the display is observed from variousdirections as compared with the case where the light scattering film isnot used, and good display performance can be achieved.

EXAMPLE

The invention will be described in detail with reference to examples,but the invention is by no means restricted thereto. In the examples“parts” and “%” mean “mass parts” and “mass %” unless otherwiseindicated.

The compounds used in the coating solutions for light scattering layersare shown below.

-   Particles 1: 0.5 μm melamine-silica crosslinked particles (OPTOBEADS    500S, refractive index: 1.65, manufactured by Nissan Chemical    Industries, Ltd.)-   Particles 2: 1.5 μm melamine-silica crosslinked particles,    refractive index: 1.65-   Particles 3: 0.1 μm melamine-silica crosslinked particles,    refractive index: 1.65-   Particles 4: 0.5 μm acryl-styrene crosslinked particles, refractive    index: 1.53-   Particles 5: 0.3 μm melamine-silica crosslinked particles,    refractive index: 1.65-   Particles 6: 1.1 μm melamine-silica crosslinked particles,    refractive index: 1.65-   Particles 7: 0.5 μm silica crosslinked particles, refractive index:    1.44 (SEAHOSTAR KE-P50, manufactured by Nippon Shokubai Co., Ltd.)-   Particles 8: 0.5 μm polymethyl methacrylate crosslinked particles,    refractive index: 1.50-   Particles 9: 0.6 μm zinc oxide particles, refractive index: 1.95    (ZINC OXIDE 1, manufactured by Sakai Chemical Industry Co., Ltd.)-   Particles 10: 0.38 μm titanium dioxide particles, refractive index:    2.52 (TA200, manufactured by Fuji Titanium Industry Co., Ltd.)

All of the particles 1-6 and 8 are used as dispersion in methyl isobutylketone (MIBK) (particle concentration: 38 wt %) dispersed with aPOLYTRON disperser at 10,000 rpm for 20 minutes.

All of the particles 7, 9 and 10 are used as dispersion in methylisobutyl ketone (MIBK) (particle concentration: 38 wt %) dispersed withan ultrasonic disperser for 20 minutes.

-   PET 30: Mixture of pentaerythritol triacrylate and pentaerythritol    tetraacrylate (manufactured by Nippon Kayaku Co., Ltd.)-   DPHA: Mixture of dipentaerythritol pentaacrylate and    dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co.,    Ltd.)-   Viscoat V360: EO-modified trimethylolpropane triacrylate    (manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY LTD.)-   DESOLITE Z7404: zirconia-containing UV-curable hardcoat liquid,    solid contents concentration: about 61%, substituted to solvent    methyl isobutyl ketone, content rate of ZrO₂ in solid contents:    about 70%, polymnerizable monomer, polymerization initiator    contained (manufactured by JSR Corporation)-   Irgacure 127: A photoinitiator (manufactured by Ciba Specialty    Chemicals Inc.)-   CAB: Cellulose acetate butyrate-   MEK: Methyl ethyl ketone-   SP-13: A fluorine surfactant

Example 1 Manufacture of Light Scattering Film Samples 101 to 109

Coating of Light Scattering Layer:

Each light scattering layer is prepared by unwinding a PET film with aneasy adhesive layer having a thickness of 40 μm from a roll, coatingwith the coating solution for forming a light scattering layer shown inTable 1 below by a die coating method using a slot die disclosed inJP-A-2006-122889, Example 1, on the condition of coating at conveyingrate of 30 m/min, and after drying at 60° C. for 150 seconds, undernitrogen-purging and oxygen concentration of about 0.1%, the coatedlayer is irradiated with ultraviolet ray of illumination intensity of400 mW/cm² and a dose of 100 mJ/cm² with an air cooled metal halide lampof 160 W/cm (manufactured by EYEGRAPHICS CO., LTD.), and a hardenedcoated layer is wound. The coating amount is adjusted so that thethickness of each light scattering layer reaches 5 μm.

TABLE 1 Coating Coating Coating Coating Coating Coating Coating CoatingCoating Coating Coating Coating Coating Solution Solution SolutionSolution Solution Solution Solution Solution Solution Solution SolutionSolution Solution A-1 A-2 A-3 A-4 A-5 A-6 A-7 A-8 A-9 A-10 A-11 A-12A-13 PET-30 14.82 14.82 14.82 14.82 14.82 14.82 18.31 10.36 0.00 10.3610.36 10.36 19.09 Viscoat 22.23 22.23 22.23 22.23 22.23 22.23 27.4715.54 0.00 15.54 15.54 15.54 28.63 V360 DPHA 0.00 0.00 0.00 0.00 0.000.00 0.00 0.00 1.67 0.00 0.00 0.00 0.00 Z7404 0.00 0.00 0.00 0.00 0.000.00 0.00 0.00 58.00 0.00 0.00 0.00 0.00 Particles 28.95 28.95 28.9528.95 28.95 28.95 5.26 59.21 28.95 59.21 59.21 59.21 0.00 (38 wt % MIBK)Irg 127 1.15 1.15 1.15 1.15 1.15 1.15 1.42 0.80 1.15 0.80 0.80 0.80 1.48MIBK 19.55 19.55 19.55 19.55 19.55 19.55 34.24 0.79 1.93 0.79 0.79 0.7937.50 MEK 12.50 12.50 12.50 12.50 12.50 12.50 12.50 12.50 7.50 12.5012.50 12.50 12.50 SP-13 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.060.06 0.06 0.06 0.06 CAB 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.750.75 0.75 0.75 0.75 Kind of Parti- Parti- Parti- Parti- Parti- Parti-Parti- Parti- Parti- Parti- Parti- Parti- None particles cles 1 cles 2cles 3 cles 4 cles 5 cles 6 cles 1 cles 1 cles 7 cles 8 cles 9 cles 10In Table 1, the unit is gram.Mounting on a Display:

The surface film of a 11 inch-organic EL television XEL-1 (manufacturedby Sony Corporation) is peeled off, and each of light scattering filmsamples 101 to 109 is stuck with an adhesive in place of the surfacefilm to manufacture a display. This organic EL television is an organicEL display using an optically resonating function, and a substrate onthe viewing side is a glass substrate having a thickness of 0.7 mm.

Evaluation of Light Scattering Film and Display:

These light scattering films and displays obtained are evaluated for thefollowing items. The results obtained are shown in Table 2 below.

(1) Refractive Index:

The refractive index of the film of each light scattering layerexcluding light scattering particles is directly measured with Abbe'srefractometer. The refractive index of light scattering particles ismeasured as follows. Two kinds of solvents arbitrarily selected frommethylene iodide, 1,2-dibromopropane and n-hexane different inrefractive index are mixed by changing a mixing ratio to obtain solventsdifferent in refractive index, and light transmitting particles aredispersed in each of the solvents in an equivalent amount and turbidityis measured, and the refractive index of the solvents at the time whenthe turbidity becomes minimum is measured with Abbe's refractometer;

(2) Asymmetry Parameter:

Asymmetry parameter g is defined by the value of the coefficient ofscattering anisotropy (the calculated value described in Bohren-Huffman,Absorption and Scattering of Light by Small Particles 3,4) and found bycalculation,

(3) Scattering Efficiency:

Scattering efficiency n×C is computed from scattering cross section Cand number of particles n based on Mic scattering theory.

(4) I₃₀/I₀:

Scattered light profile of a light scattering film is measured with agonio-photometer. A light scattering film is arranged vertically toincident light with an automatic deflection angle photometer Model GP-5(manufactured by Murakami Color Research Laboratory) and the scatteredlight profile is measured, and found as the calculated value of I₃₀/I₀with the value in the direction of 0° (direct advance direction) of theforward scattering factor being I₀, and the value in the direction of30° (the direction inclined by 30° from the direct advance direction) ofthe forward scattering factor being I₃₀.

(5) Tint of Viewing Angle:

In white displaying of the display, the direction at a right angle(front) to the display is taken as 0°. The angle is inclined to 80° inthe transverse direction, and variation of tint is visually observed ina dark room, and judged by the following criteria

-   A: Variation in the tint with the change of angle is hardly seen,-   B: Variation in the tint with the change of angle is seen but not    annoyed,-   C; Variation in the tint with the change of angle is annoyed.    (6) Frontal Luminance:

In white displaying of the display, luminance is observed at the frontof the display in a dark room, and frontal luminance as compared withthe time not sticking the light scattering film is judged by thefollowing criteria.

-   A: Change in luminance by sticking a light scattering film does not    jar upon feelings.-   B: Change in luminance by sticking a light scattering film jars upon    feelings but is not a matter for use.-   C: Change in luminance by sticking a light scattering film jars upon    feelings and is somewhat problematic.-   D: Change in luminance by sticking a light scattering film is great    and on a problematic level.    (7) Feeling of Discoloration:

In black displaying of the display, the display is observed at the frontand feeling of discoloration is evaluated in a bright room by thefollowing criteria.

-   A: Discoloration is not perceived.-   B: Discoloration is perceived a little but is not a matter for use.-   C. Discoloration is perceived and somewhat problematic.-   D: Strongly discolored and on a problematic level.    Central Line Average Roughness (Ra):

Central line average roughness (Ra) (μm) is measured with SurfcorderMODEL SE-3F (manufactured by Kosaka Laboratory Ltd.) in conformity withJIS-80601.

Average Reflectance:

The rear face of a film is roughened with sand paper, and then treatedwith black ink to get rid of rear face reflection. The spectralreflectance of the front face side is measured in the wavelength regionof from 380 to 780 nm with a spectrophotometer (manufactured by JASCOCorporation). The result is obtained by the arithmetic mean value ofintegrated reflectance and mirror reflectance of from 450 to 650 nm.

The maximum value of emission wavelength of the display in the inventionis in the range of 350 nm or more and 700 nm or less, and[(x₆₀-x₀)²+(y₆₀-y₀)²]^(1/2) is in the range of 0.08 or more and 0.25 orless, taking the color coordinate of emission spectrum in the directionof output angle of 0° on xy chromaticity diagram as (x₀, y₀) and thecolor coordinate of emission spectrum in the direction of output angleof 60° as (x₆₀, y₆₀).

The results of evaluations are shown in Table 2 below. From Table 2, itcan be seen that since the organic EL displays in the invention have alight scattering film having specific optical performances according tothe invention, as compared with the case of not using a light scatteringfilm, good display performances can be achieved such that variation oftint is little when images on the display are observed from variousdirections, lowering of the frontal luminance is little, and feeling ofdiscoloration is also little.

In each light scattering film, integrated reflectance is 4.5%, a* valueis in the range of from 0 to 0.2, b* value is in the range of from −1.0to 0, and reflected colors are neutral but mirroring in to the surfaceis on a level somewhat jarring upon feelings. In all the lightscattering films in the invention, central line average roughness isfrom 0.03 to 0.18 μm.

TABLE 2 Refractive Refractive Content Index of Particle Index of of FilmAsymmetry Sample Coating Binder Size Particles Particles ThicknessParameter No. Solution (nb) Particles (μm) (np) np/nb (wt %) (μm) (g)101 A-1 1.52 Particles 1 0.5 1.65 1.09 22 5 0.88 102 A-2 1.52 Particles2 1.5 1.65 1.09 22 5 0.97 103 A-3 1.52 Particles 3 0.1 1.65 1.09 22 50.13 104 A-4 1.52 Particles 4 0.5 1.53 1.01 22 5 0.89 105 A-5 1.52Particles 5 0.3 1.65 1.09 22 5 0.76 106 A-6 1.52 Particles 6 1.1 1.651.09 22 5 0.96 107 A-7 1.52 Particles 1 0.5 1.65 1.09 4 5 0.88 108 A-81.52 Particles 1 0.5 1.65 1.09 45 5 0.88 109 A-9 1.62 Particles 7 0.51.44 0.89 22 5 0.90 110 A-10 1.52 Particles 8 0.5 1.50 0.99 22 5 0.89111 A-11 1.52 Particles 9 0.6 1.95 1.28 22 5 0.87 112 A-12 1.52Particles 10 0.38 2.52 1.66 22 5 0.68 113 A-13 1.52 None — — — — 5 —Scattering Tint of Sample Efficiency Viewing Frontal Feeling of No. (e)I₃₀/I₀ Angle Luminance Discoloration Remarks 101 1.15 0.63 A A AInvention 102 2.87 0.02 C A A Comparison 103 0.08 0.98 A D D Comparison104 0.01 0.63 B B B Comparison 105 0.60 0.85 A B B Invention 106 2.400.09 B A A Invention 107 1.15 0.63 B A A Invention 108 1.15 0.63 A B BInvention 109 1.58 0.65 A A A Invention 110 0.02 0.64 C B B Comparison111 10.52 0.48 B C C Invention 112 25.09 0.72 A D D Comparison 113 — — CA A Comparison

Example 2

A low refractive index layer mainly comprising a fluorine polymer andhollow particles having a refractive index of 1.36 is formed in athickness of 90 nm on the light scattering layer of the light scatteringfilm of the invention in Example 1. The integrated reflectance afterforming the low refractive index layer is as low as 2.0% in contrast tothe integrated reflectance of 4.5% before forming the low refractiveindex layer, so that reflection is restrained, and the display aftermounting each sample is good in the improvements of viewing angledependency of tint, frontal luminance, and feeling of discoloration, inaddition the enhancement of black in a bright room is bettered.Incidentally, the mirror reflectance after forming the low refractiveindex layer is from 1.5% to 1.7%.

Example 3

An intermediate refractive index layer mainly comprising DPHA andzirconia fine particles (particle size: about 10 nm) having a refractiveindex of 1.62, a high refractive index layer having a refractive indexof 1.72, and a low refractive index layer mainly comprising a fluorinepolymer and hollow particles having a refractive index of 1.36 areformed in this order respectively in thickness of 60 nm, 110 nm and 90nm on the light scattering layer of the light scattering film of theinvention in Example 1. The integrated reflectance after forming threelayers is as low as 0.9% in contrast to the integrated reflectance of4.5% before forming three layers, so that reflection is restrained, andthe display after mounting each sample is good in the improvements ofviewing angle dependency of tint, frontal luminance, and feeling ofdiscoloration, in addition the enhancement of black in a bright room isfurther bettered. Incidentally, the mirror reflectance after formingthree layers is from 0.5% to 0.9%, and a* value is in the range of from0 to 3, b* value is in the range of from −4 to 0. Reflected colors arcvery neutral and display grade at the time of black displaying isexcellent.

Example 4

A display is manufactured in the same manner as in Example 1 except forusing a glass substrate having a thickness of 0.1 mm as the substrate onthe viewing side of the organic EL display in Example 1. The surface andedges of the glass substrate are coated with a polymer obtainable byhydrolytic polycondensation of tetraethoxysilane, γ-acryloxy propyltrimethoxysilane and γ-amino propyl trimethoxysilane. Thereby, viewingangle dependency of tint, frontal luminance, and feeling ofdiscoloration of the organic EL display using the light scattering filmin the invention are improved, and the display can be lightened andfeeling of a blur of an image can be further restrained.

Example 5

A display is manufactured by directly forming a laminate comprising alight scattering layer, a low refractive index layer, an intermediaterefractive index layer, a high refractive index layer, and a lowrefractive index layer on a water vapor barrier film in the same manneras in Example 3 and using it as a substrate on the viewing side, andevaluated. The water vapor barrier film has a water vapor permeation of0.005 g/m²·day at 40° C. 90% RH and is a laminate comprising a 40 nmpolyethylene naphthalate film having thereon an acrylic organic resinlayer formed by a coating system, and a silica thin layer formed by asputtering system. Thereby, viewing angle dependency of tint, frontalluminance, and feeling of discoloration are improved and, further, thedisplay can be lightened and feeling of a blur of an image can berestrained. In addition, an image having good durability can bemanufactured.

Since the organic EL displays in the invention have a light scatteringfilm having specific optical performances according to the invention, ascompared with the case of not using a light scattering film, gooddisplay performances can be achieved such that variation of tint islittle when images on the display are observed from various directions,lowering of the frontal luminance is little, and feeling ofdiscoloration is also little. Moreover, the organic EL displays in theinvention have characteristics such as light weight, thin, and little ina blur of letters. Further, the displays in the invention are excellentin manufacturing suitability, selectivity of materials and durability.

By using the technique in the invention, an organic EL display improvedin viewing angle dependency can be provided. The invention can alsoprovide a thin type organic EL display restrained in a blur of letters(reduction of image resolution) can be provided. Further, theimprovement of frontal contrast can be achieved at the same time. Theinvention can provide an organic EL display having these effects in highproductivity.

The entire disclosure of each and every foreign patent application fromwhich the benefit of foreign priority has been claimed in the presentapplication is incorporated herein by reference, as if fully set forth.

1. An organic electroluminescent display comprising: a pair ofsubstrates; an organic electroluminescent device between the pair ofsubstrates, comprising: a pair of electrodes of an anode and a cathode,and a light-emitting layer between the pair of electrodes; and a lightscattering film on a substrate on the viewing side of the pair ofsubstrates, comprising: a transparent substrate film, and a lightscattering layer which contains a light transmitting resin and a lightscattering particle having a particle size of from 0.3 μm to 1.2 μm,wherein a ratio of (np/nb) is from 0.80 to 0.95 or from 1.05 to 1.35,taking a refractive index of the light scattering particle and the lighttransmitting resin as np and nb, respectively, and the light scatteringfilm has asymmetry parameter (g) of from 0.70 to 0.98.
 2. The organicelectroluminescent display of claim 1, wherein the particle size of thelight scattering particles is from 0.4 μm to 1.0 μm.
 3. The organicelectroluminescent display of claim 1, wherein the light scattering filmhas a scattering efficiency (e) of from 0.05 to 12.0.
 4. The organicelectroluminescent display of claim 1, wherein a ratio of (I₃₀/I₀) isfrom 0.08 to 0.99, taking a scattered light intensity of a scatteredlight profile by a gonio-photometer at output angle 0° and 30° as I₀ andI₃₀, respectively.
 5. The organic electroluminescent display of claim 1,wherein the light scattering film is an antireflection film comprising alow refractive index layer, directly or via any other layer, on asurface of the light scattering layer, and an average value of mirrorreflectivity at 5° incidence of the antireflection film in a wavelengthregion of from 450 to 650 nm is from 0.1% to 2.0%.
 6. The organicelectroluminescent display of claim 5, wherein the tints of regularlyreflected light of the antireflection film to 5° incident light of CIEstandard light source D65 in a wavelength region of from 380 nm to 780nm as a* and b* values of CIE1976L*a*b* color space are respectively ina range of −8≦a*≦8 and −10<b*<10.
 7. The organic electroluminescentdisplay of claim 1, wherein a center line average roughness (Ra) on asurface of the light scattering film is from 0.003 μm to 0.20 μm.
 8. Theorganic electroluminescent display of claim 1, wherein the transparentsubstrate film has a thickness of from 10 μm to 80 μm.
 9. The organicelectroluminescent display of claim 1, wherein the transparent substratefilm has a water vapor permeability of 0.01 g/m²·day or less at 40° C.90% RH.
 10. The organic electroluminescent display of claim 1, wherein amaximum value of emission wavelength is from 350 nm to 700 nm, and[(x₆₀−x₀)²+(y₆₀−y₀)²]^(1/2) is from 0.05 to 0.3, taking a colorcoordinate of emission spectrum in a direction of output angle of 0° and60° on xy chromaticity diagram as (x₀, y₀) and (x₆₀, y₆₀), respectively.11. The organic electroluminescent display of claim 1, wherein a lightreflected between the surfaces of both electrodes is opticallyresonated.
 12. The organic electroluminescent display of claim 1,wherein the substrate on the viewing side has a thickness of from 0.01mm to 0.70 mm.
 13. The organic electroluminescent display of claim 1,wherein the substrate on the viewing side has a thickness of from 0.03mm to 0.30 mm.
 14. The organic electroluminescent display of claim 1,wherein at least one of the surface and the edge of the substrate on theviewing side is coated with a polymer.
 15. The organicelectroluminescent display of claim 1, wherein the substrate on theviewing side is a gas barrier film.
 16. An organic electroluminescentdisplay comprising: a pair of substrates; and an organicelectroluminescent device between the pair of substrates, comprising: apair of electrodes of an anode and a cathode, and a light-emitting layerbetween the pair of electrodes, wherein at least a substrate on theviewing side of the pair of substrates is a light scattering filmcomprising: a gas barrier film having a water vapor permeability of 0.01g/m²·day or less at 40° C. 90% RH, and a light scattering layer whichcontains a light transmitting resin and a light scattering particlehaving a particle size of from 0.3 μm to 1.2 μm; and a ratio of (np/nb)is from 0.80 to 0.95 or from 1.05 to 1.35, taking a refractive index ofthe light scattering particle and the light transmitting resin as np andnb, respectively.